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4x^2-21x-18=0
Find the discriminate

User PandaNL
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2 Answers

4 votes

Answer:729

Step-by-step explanation: Use the values of a, b and c to find the discriminant. Which is 729

User Muhammad Shareyar
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5.8k points
7 votes

a = 4, b = -21, c = -18

to keep from getting "mixed up", evaluate the discriminant first ...

b<sup>2</sup> - 4ac = (-21)<sup>2</sup> - 4(4)(-18) = 729

sqrt(729) = 27

x = (21 +/- 27)/8

x = -3/4, x = 6

since the discriminant is a perfect square, the original quadratic will factor ...

4x<sup>2</sup> - 21x - 18 = 0

(4x + 3)(x - 6) = 0

x = -3/4, x = 6

User Francesco Galletta
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5.1k points